This invention relates to a process, and to an apparatus, for conditioning cables or webs consisting of synthetic fibres by means of steam, more particularly filaments and fibres of acrylonitrile polymers with at least 40% by weight of acrylonitrile units, optionally after crimping.
Perforated drum steamers and perforated belt steamers are preferably used as apparatus for steaming continuously conveyed synthetic fibre material (e.g. in DE-OS No. 2 060 941 or GB-PS No. 1 208 792). Steam tubes, steam tunnels and U-shaped steam cylinders, c.f. e.g. Textilpraxis international December 1981, page 1410 or Chemiefasern/Textilindustrie November 1981, page 821 or February 1982, page 96, have also become known. Combinations of crimping apparatus with connecting fixation chambers (e.g. U.S. Pat. No. 2,865,080) are also described in various forms and embodiments, particularly for texturising and fixing processes. These steam aggregates are used for drying and shrinking fibre cables and for stabilising the crimping and spin dying of the fibres.
In EP-OS No. 98 477 is described firstly a continuously-operating dry spinning process for acrylonitrile filaments and fibres, in which the tow of 100,000 dtex or more is prepared, shortly before or directly after leaving the spinning shafts, is then stretched, crimped and fixed, without the cable contacting a liquid for extracting the spinning solvent, for example, water. Most of the spinning solvent is expelled in the spinning shafts in this process. The solvent content of the filaments on leaving the spinning shafts is generally less than 10% by weight, based on the fiber solids content, but more than 1% by weight.
Known conditioning apparatus are not suitable for this process. The required quantities of steam are either too high or else damage to the natural tone, or felting, of the fibre cable occurs.